Factis

Ruby DSL for safely tracking facts through a test

Gem Setup

gem install factis

# Gemfile
group :test do
  gem 'factis'
end

Using with Rails

Included are a couple of generators to help you get rolling with Rails apps.

Cucumber

rails generate factis:cucumber

Truth be told, this just installs some example Factis steps and a support file for Cucumber. For the time being, it's on you to figure out how to use it with other testing frameworks.

factis_steps.rb

Much like our once beloved web_steps.rb, you should read factis_steps.rb exactly one time, and then you should delete it. It's really just an example, and using those steps in a feature will make your stakeholders hate you with the fury of a thousand burning suns.

Rspec

rails generate factis:rspec

This adds a Factis support file to your spec tree. The default configuration is the same of that for Cucumber. It's important to note that Factis is brought into Rspec via config.include so the DSL is available in the examples, but not in the overall environment.

Manual Cucumber

So, using Cucumber, but not Rails? Try this!

# features/support/factis.env
require 'factis/cucumber'

This gets you ready to use the DSL. Additionally, it forces Factis to forget everything that you have told it to memorize after each scenario. Because stale state information from one scenario to the next will make you a very sad panda.

Manual Rspec

So, using Rspec, but not Rails? Try this!

# spec/support/factis.rb
require 'factis/rspec'

If you're not using an all-inclusive support directory for your specs, you can just toss that require into your spec_helper.rb or what have you.

This gets you ready to use the DSL. Additionally, it forces Factis to forget everything that you have told it to memorize after each example. Because stale state information from one example to the next will make you an increddibly depressed platypus.

The DSL methods are injected into Rspec via include, so they're available anywhere that example-level helpers are available. Primarily, in examples and before/after callbacks.

How Do I Use This Thing?

When I'm tracking state within a test, it's most likely a Cucumber feature. That being the case, I'm going to use terminology from that side of the experience. Here's everything that World gets when you use Factis.

# Let's memorize that my brother, Joe, just loves cake.
memorize_fact("What does Joe love?", "Joe loves cake.")
  => "Joe loves cake."

# Wait, I had that wrong. Joe loves pie.

memorize_fact("What does Joe love?", "Joe loves pie.")
  => Cannot memorize a fact more than once: 'What does Joe love?' (RuntimeError)

# Why does that happen?
# Er, because we're trying to track state safely, and overwriting states
# all willy-nilly is kinda unsafe.
# So, how do I overwrite a known fact?
# If you want to unsafely track state, you should probably just use global
# variables. Shooting from the hip never did anybody wrong, after all. Or, you
# can use indifferently_memorize_fact, which is a bad thing to do.

indifferently_memorize_fact("What does Joe love?", "Joe loves pie.")
  => "Joe loves pie."

# Hey Factis, what does Joe love?
recall_fact("What does Joe love?")
  => "Joe loves pie."

# That's not very interesting. Let's forget about it.
forget_fact("What does Joe love?")
  => "Joe loves pie."

# Wait, what does Joe love again?
recall_fact("What does Joe love?")
  => Trying to recall an unknown fact: 'What does Joe love?' (RuntimeError)

# Just to make sure it's really forgotten ...
forget_fact("What does Joe love?")
  => Trying to forget an unknown fact: 'What does Joe love?' (RuntimeError)

# Let's just forget everything.
clear_all_facts!

# So, what facts do we know?
all_facts
  => {}

class Foo
end

# The content can be pretty much anything.
memorize_fact(:some_foo, Foo.new)
  => #<Foo:0x007ffd84394728>

# What's a foo?
recall_fact(:some_foo)
  => #<Foo:0x007ffd84394728>

Formal Documentation

The actual library docs can be read over on rubydoc.

Contributing

Do you use git-flow? I sure do. Please base anything you do off of the develop branch.

1. Fork it.
2. Perform some BDD magic. Seriously. Be testing.
3. Submit a pull request.

So, Uh, Why?

There are two sides of this story, really:

• It's generally accepted that being able to track things over the course of an idempotent test (a user's email address, the number of stars in the known galaxy, etc) makes it easier to write tests. Rather than thinking "my email address is [email protected]" repeatedly, you can just accept that you have an email address.

• It's generally accepted that tracking things with instance variables over the course of a test is a pretty bad scene. On top of generally muddying up the object space, it makes it really easy to rely on state that's left over from a previously-run scenario, forget to set them up in the first place, etc.

I've run into a lot of problems with tracking state in my tests in unsafe ways, so this thing got thrown together.

Okay, So What's So Great About It?

Not much, really. It's just a simple DSL that hides away the things that you tell it to memorize and recalls them at your request. There is a generator to get you up and running with Cucumber, but you should be able to use it with just about any test framework that allows you to extend the global namespace (a-la World(Factis)).

License

MIT License. Copyright 2013 Ess